Automatic circuit breaker



y 30, 1940. P. M. CHRISTENSEN 2 3 9 AUTOMATIC CIRCUIT BREAKER Filed NOV. 28, 1938 Patented July 30,` 1940 UNITED STATES 'PATENT OFFICE I zanatit AU'roMA'rc cmcU'r BBEAKEE.

necticut Application November 28, 1938,` Serial Naa-12,763

16 Claims. (Ci. 200-116) The present invention relates particularly to a circuit breaker having some of the characteristics of that disclosed in the co-pending application of Joseph sachs for Automatic circuit break ers, Serial No. 152,020, filed July 6, 1 937, and

having some, of the characteristics of that disclosed in the co-pending application of Joseph Sachs and Paul M. Christensen for Automatic circuit `breakers, Serial No. 202295, filed. April The general object of the invention is to provide an automatic clrcuit breaker of the general character above set forth, but having certain improvements in arrangement of parte and in structural details' which make it possible for it to be manufactured at lower cost while retaining high efliciency and reliability of operation.

In accordance with one phase of the present invention, the contact member is pivotally mounto ed between its ends and the pivot pins for the contact member and for the Operating member are mounted directly in the main insulating housing, thus avoiding the necessity for separate frame'members and at the same time obtaining other advantages as will more fully appear from the specification. v

In accordance with another phase oi the invention, the resilient link forming a part of the toggle linkage is provided with integral pivot ao portions, the link being preferably formed of a single piece of wire.

In accordance .with another phase of the inventioh a single spring is provided which serves to properly bias both the pivoted contact member and the pivpted Operating member.

In accordance with stili another'phase of the construed as defining or limiting the scope of the invention, the claims forming a part of this specification being relied upon for that purpose.

Of the drawing: x 50 Fig. 1 is a front view of a circuit breaker assembly embodying the invention. Fig. 2 is a fragmentary side view of the assembly shown in Fig. 1.

Fig. 3 is an enlarged fragmentary front view u of the lower right hand unit and associated parts u as shown in Fig. i, the front cover plate being omitted.

g Fig. 4 is an enlarged vercal sectional View taken along the line 4-4 of Fig. 1`.

Fig. 5 is an enlarged bottom view of the mech- 5 anism of the lower right hand unit, the housing being shown in section along the line 5-5 of Fig. 4.

Fig. 6 is an enlarged perspective view of a conductor with stationary contacts carried ;thereby. 10

Fig. 7 is an enlarged fragmentary sectional view taken along the line '5-1 'of Fig. 4.

Fig. 8 is a view similar to the lower portion of Fig. 4, but showing the parts in the positions' which they assume upon automatic opening 15 while the handle is held in closed-circuit posltion.

Fig. 9 is a perspective view showing an alternative resilient link adapted to be substituted for the link shown in Figs. 3, land 5. V n

Fig. 10'is an enlarged fragmentary view of some of the parts shown in the lower portion of Fig. 4.

Fig. 11 is a fragmentary sectional View taken along the line I i--I I 'of Fig. 10. i

As to some of the features of the invention, sa I do not narrowly limit myself as concerns the character of the housing in which the circuit breaker mechanism is mounted. As to other features, however, the housing is important and I will describe one suitable housing which coai) operates with the mechanism to provide certain novel characteristics.

Referring first to Figs. 1 and 2, the main insulating housing is represented at i. The housing, as shown, is adapted for holding or contain- :5 ing four separate circuit breaker mechanisms but I do not nccessarily limit myself as to the exact number. Fig. i shows two similar housings I, i Secured to a common supporting plate 2, by means of screws or rivets 3, 3. However, so :far as the 40 invention is concerned, the number of housings is immaterial. A

It will be understood that the housings with the mechanisms contained therein are ordinarily enclosed in a suitable casing; but the casing is omitted from the drawing as it forms .no part of the present invention. The co-pending application of Joseph Sachs for Automatic circuit breaker assembly, Serial No. 202297, filed April 15, 1938, shows a suitable casing, and also shows V suitable means whereby -a supporting plate such as 2 can be detachably mounted in the casing.

As sl. wn, the housing l is an integral structure molded from a suitable insulating material. It has four mechanism containing chambers 4, s

.a 5, S and 'i therein, all initially open at the front.

The ,upper chambers 6 and '5 are initially open at the top and the lower chambers 6 and 1 are initially open at the bottom and all of the chambers are initially in communication with a main central chamber 8.

Each housing l has a front cover 9 which may be of metal,- an insulating sheet 9 being interposed between the cover and the housing. The cover 9 and the sheet 9 'willbe referred to col lectively as constitutingthe frontcover plate. The front cover plate is held in place by screws il carries on itsrear face four rearward facing stati'onary contacts !3, it positioned respectively at the lower ends of the chambers i and 5 and at the ;upper ends' of the chambers B and 1. The

conductor H extends to the exterior of the housing at the right and is there provided with a suitable wire terminal N. A partition plate !5 v of insulating material is fitted within grooves near the open right end of the chamber 8 so as to partly close the said open end after the conductor H has been put in'place.

In addition to the stationary contact s which is provided for each mechanism, there is also provided a stationary conductor which is at the opposite endof the chamber. Each of these conductors is provided with a suitable wire terminal. The wire terminals for the mechanisms in the chambers i and 5 are at the top, being marked !E and l'l and the wire terminals for the chambers 6 and 'l are at the bottom, being marked 58 and se. The several conductors'and wire ter- 'minals are held in place by screws extending forward through the main body of the housing as clearly illustrated in Fig. 4. Directly connected with each of -the last mentioned con ductors and wire terminals is a flexible conductor 20.

Transverse partition plates are provided at the tops and bottoms of the several chambers i, 5, 9 and I, these being insulating plates fitted in suitable rearward extending grooves in the side walls of the chambers. These partition plates are held in place by the front cover plate. As shown in Fgs. 3 and 4, the upper chamber 4 has a partition plate' 2! which substantially closes the chamber at the top, and the lower chamber 6 has a similar partition plate 22 which substantially closes 'the chamber at the bottom. The chambers 4 and 6 are respectively separated from the central chamber 8 by partition plates 23 and 24.

` In the detailed description which follows, reference will be had chiefly to the circuit breaker mechanism contained in the lower right hand chamber S but reference will alsob had to the mechanism contained in the upper right hand chamber 4. All of the mechanisms are identicalin construction or substantiay so, but'the upper and lower mechanisms are reversed as to positions* A mo'fable contact member 25 is* provided which is pivotally mounted between its ends. The contact member hasa transverse pivot pin 26 which extends into'grooves 21-; 21 formed in the side walls of the mechanism containing chamber. These grooves are closed at rear ends and their closed end portions therefore serve as bearings' for the pivot pin. The contact member 25 is preferably a single piece of sheet metal oli'set transversely near the-pivot pin 26 as indicated a at ZE. Carried by the contac member near one end thereof is a forward facing 'the front face of the housing. The front cover' plate cooperates with the pivot pin 30 to hold it in place in the bearing notches. A portion of the Operating member 29 projects forward through the corresponding opening in the front cover plate so as to be accessible for convenient manual operation. At the rear of the front cover plate the Operating memberis provided with integral portions 29 and %E which are adapted to contact with the frontj cover plate to limit the movement of the Operating member in both directions.

The contact member 25 and the Operating member 29 are both biased for movement toward their open-circuit positions, and preferably and in accordance with one phase of the present in- V vention, the biasing of both of these members is eifected by means of, a single spring 32. The spring 32 is shown as being a coil spring having extending end 'portions which are entered re'- spectively in holes formed in the contact member and in the Operating. member. The spring tends to 'open or separate, thus tending to move the contact member 2 5 in the clockwise direction and tending to move the Operating member 29 in the counter-clockwise direction.

. In order that the Operating member 29 may operate thefcontact member 25, there is provided a connecthg mechanism which includes an actuator 33. The actuator is pivotally connected with the contact member near the end thereo! which is opposite the end 'carrying the movable contact 28. The actuator is controlled by means of a bi-metallic element 34 which is bodily movable with the contact member 'and 'which serves in and of itself as a latch' cooperating directly with the actuator 33. The pivotal connection of the actuator 33 with the contact member 25 is effected by means of a* pivot pin 35. The

actuator is insulated from the contactmember line connecting the pivotal axes at 30 and 39,

the Operating member itself thus cooperating with the link 36 to form -a normally locked or overset toggle. The beforementioned stop 29,' on the Operating member engages the front cover to limit movement thereof` in the clockwise direction. I s

The before-mentioned bi-metallic latch 34 normally engages at its lower end with the actuator 33 and it holds the actuator in its normal relationship with the other parts as shown in the lower portion of Fig. 4. The upper end of the latch is rigidly secured by brazing or otherwise to the edge of the sheet .metal element 25 which constitutes the contact member, the connection being near the center. *The beforementioned flexible conductor 20 is electrically connected directly with the bi-metallic latch 34 near the lower latching end thereof. This connection may be efifected by brazing.

With the circuit breaker mechanism in closedcircuit position as shown in the lower portion of Flg. 4, it will be apparent that electrical connection is established from the conductor H and the stationary contact l3 to the movable contact 28, thence through the contact member 25 and the bi-metallic latch 34, and thence through the flexible conductor 20 to the stationary conductor and wire terminal !8 at the bottom. As already stated, the contact member is biased in the clockwise or circuit-opening direction by means of the spring32, and the Operating member is biased in the counter-clockwise or circuit-opening direction by means of 'the same spring. However, actual movement in the' circuit-opening direction is normally prevented by reason of the described overset toggle relationship between the Operating member itself and the link 36, it being understood that the latch 34 normally holds the actuator 33 from relative movement in the counter-clockwise direction. Normally the operating member 29 may be moved to move the contact member in either direction and thus open or close the circuit. During such normal movements the latch 34 remains engaged with the actuator 33.

If the handle or Operating member-be held in its closed-circuit position as shown in the lower portion of Fig. 4, and if an abnormal current condition such as an overload is attained, the bimetallic latch 34 is automatically deflected rearward, this deflecti'on occurring as the result of the heating of the bi-metallic latch by the current flowing therein. This rearward deflection causes the latch to disenga'ge and release.` the actuator 33. When the actuator is no longer held by the latch, the entire contact member is moved by the spring 32 to its open-circuit position as shown in Fig. `8, the actuator 33 and the link 36 assuming the relative positions shown in that figure. If the Operating member be released after the parts have moved to the relative positions shown in Fig. 8, the spring 32 moves the Operating member to the position shown in the upper portion of Fig. 4, this in turn moving the link 36 and the actuator 33 to the positions there shown. The actuator 33 is thus restored to engaged or engageabie relationship with the bimetallic latch 34.

The operation has been described as it occurs when the handle is' first held and then released. Ordinarily, however,` the Operating member is not held and it starts to move to its open-circuit position as soon as the actuator has moved far enough to break the looking reiationship between the Operating member 29 and the link 36. All of the parts ths move pr'actically instantaneously to the position shown-in the upper portion of Fig. 4, the actuator being immediately restored to engaging relationship with the latch. As soon as the latch has cooled sufliciently the .Operating member can be moved to again close the circuit. It will be observed that in the open-circuit position as shown in the upper portion-of Fig. 4; the stop 29 'engages the front cover plte to limit movement o! the Operating member.

When any one o! the movable contacts 26 is separated from the corresponding 'stationary contact !3, either manually or by automatic action, any gases that may be formed by the resultant arc pass into the central chamber 8 which has been referred to. In order that these gases mayescape to the exterior of the housing, the chamber 8 is preferably provided at one side with notches ti' B as shown in Figs. 1 and 2. It

will be observed that the partition plat'es 23 and u 241 prevent any considerable portion of these are-formed gases from passing upward or downward into contact with the circuit breaker mechanism.

In accordance with one phase of the present invention, I provide a novel and advantageous construction for the link-36. As shown, particularly in Figs. 3, 4 and 5, the link 36 is formed from a single piece of metallic wire, the link having two integral pivot portions 36 and 36 and having a connecting portion 36 between the two pivot portions. The two pivot portions 33 and 36 are 'entered directly in holes formed respectively in the Operating member and the actuating member at 31 and 38. The adjacent housing wall holds the link in place and prevents any undue lateral movement thereof. The construction of the links 36 from a single piece of wire greatly reduces costs, as it eliminates the cost of machining or otherwise forming a 'link with bearing apertures therein, and it eliminates the necessity for separate pivot pins.

In a circuit breaker of the general character herein shown and described, it is necessary to provide resiliently acting means for insuring the required pressure between the Contacts. As disclosed in the before-mentioned Sachs and Christensen application, Serial No. 202295 the stationary contact is rigidly or fixedly se'cured in place so that no appreciable 'movement is possible, and the movable contact is rigidiy Secured to the contact member so that it cannot move relatively thereto. The necessary resiliency in or in association with 'the train of mechanism for moving and holding the contact member is provided by means of a resilient link between the Operating member and the actuator. Ian the present construction the principle of the resilient link is retained, and the connecting portion 3.6 of the link 36 is resilient, being of loop form as shown. The resiliency of the link 36 permits it to yieid as the toggle approaches its overset relationship. In moving the mechanism from the opencircuit position as shown in the upper portion of Fig. 4 to the closed-circuit position as shown in the lower portion of the same figure, the contacts are brought into engagement just before the toggle reaches its dead center position. Continued pressure on the handle or Operating member serves to compress' the link 36 until the dead center position is reached, the link serving to apply the required contact pressure. When the handle or Operating member is moved beyond the dead center position to the closed-circuit position, the force resiliently applied by the link 36 -serves not only to maintain .the contact pressure but also to hold the toggle in the overset position as shown.

In lieu of the spring 36 shown in Figs. 3, 4 and 5, I mayuse an alternative form of spring 39 as shown in Fig. 9. This spring 39 is of the same -general'character as the spring 36, but it is provided not only with two integral pivot portions 3!! and 33 but also with two transversely spaced resilient connecting or loop portions 39, 39. The

'resiliency of the link permits the two parts of the pivot portion33 to be sprung apart so that the apart and then permitted 'to snap into the hoe t 31 in the Operating member 29. With the spring 39 as constructed as shown in Fig. 9, I avoid any tendency for the two pivot portions to be forced out of parallelism with each other, and I .thus provide a more direct and reliable resilient connection between the Operating member and the .actuator.

Referring particularly to Fig. 8, it will be observed that with the parts positidned as there shown the pivot pin 26 is held at the rear ends of the slots ll partly bythe expensive action of the spring 32. If no other means were provided for so .holding the pivot pin, there would be some tendency for it to move forward when the operating member.. is moved to closed-circuit position for re-cngaglng the actuator with the latch. This would be particularly true if the latch had in the' meantime cooled and returned to its normal position so that a substantial amount of force would be required to move the actuator 'into' its normal latch 'engaging position. In order to make it impossible for the pivot pin 26 to move forward as stated, it' may be desirable to provide a suitable stop for engaglng the contact member 25. As shown, the contact member 25 is provided with an extension 25 which engages a transverse insulating .plate M fitted in suitable slots in the side walls of the housing chamber and held in place by the front cover plate.

It is ordinarily preferable to provide a means r for efiecting fine adjustments of the bi-metallic ;limit myself.- r

Referring particularly to Figs. o and 11', it will be seen that the contact member has a longi-- tudna' slot :s therein; this slot being near-the rear edge and adjacent the point of attachment of the 'bimetallic element 34. The slot 25 is preferably closed .at both ends" although this is not absolutely essential. The slot 25 provides an edge. portion oi' the contact member which is readily distortable in a direction parallel with the faces of the plate and which when distorted .serves to move the'bi-metallic element 34 so as to change its relationship with respect' to the main body of the contact member and with respect to the actuator. In order to effect distortion of thebeforementioned distortable edge portion of the contact member, I preferably provide a threaded liole whichls so positioned as to A tapered screw;

ll is threaded into this hole, and it will be clear be intercepted bythe 'slot 25.

that when the screw'is turned and forced into 'the bole, it will distort the edge portion .of the conthe said distortableedge' ortion may be distorted fromthe position sh wn by dotted lines in Flg; to the position shown by full lines. This distortion of the edge portion of 'the contact member will move the'bi-nietallic latch from the position shown by dotted lines in Fig. 10 to the position shown in full lines.

It will be understood that the final adiustment o! the screw CI to eflect calibration should be made after the operating parte have been completely 'assembled and made ready !or testing.

In practice the'rront cover plate first secured aeoaaa 'said parts of the pivot portion t to be Sprung by means of .the screws w, lil, but the rivets 3, 3 are omitted, the. housing I being not yet mounted onthe supporting plate 2. The housing i is provided with openings 32, 62 adjacent the respective screws ti, ll, so that the said screws remain accessible for final calibration. After the completion of calibration, partition plates 33, t are inserted in suitable slots in the edges of the openings 02. Then the housings are mounted on the supporting plate 2 and are secured in place by means' of the rivets 3. 'I'hus the partition plates 33 are locked in place and it becomes impossible for the user of the circuit breaker to tamper with the 'adjusting screws ll What I claim is:

1. The combination in an automatic circuit breaker, of a stationary contact, a stationary conductor separate from the said contact, a flexible conductor electrically connected at one end with the stationary conductor, a movable contact member pivotally mounted between its ends and including near one end a contact adapted to. engage and disengage the stationary contact, the said member being biased in the contact disengaging direction, a"bodily` movable bi-metallic latch on the contact member electrically con- 'nectedbetween the movable contact and the other end of the fiexible conductor, the said latch being autmatically defiected i'rom its normal relationship-with the contact member upon the deflectionof the latch to permit'automatic cir- 'cuit-opening'movement of the contact member,

and means for Operating the actuator to enable 40 it in cooperation with the latch to normally efiect the movement of the contact member or to normally hold it in contact engaging position.

2. The combination in an automatic circuit breake'r, of an insulating housing comprising two spaced side walls having opposite similar closedend grooves extending rearward from the front of the' housing and also having two transverse registering hearing notches additional to the said rearward extending grooves, a rearward facing po stationary contact in the housing, a contact` member including a forward facing contact near 'one end adapted to engage and disengage the stationary contact, the said contact member having between its ends a pivot pin entered in the rear 355 closed .ends of the aforesaidgrooves, an Operating member having a pivot pin entered in the aforesaid `beariiig notches, and an electro-responsively releasable mechanical connection between the Operating member and the other end of the conao tact 'member normally enabling the' Operating I tact member adjacent the slot. For instance, member to move the contact member' 3. The combination in an automatic circuit breaker, of an insulating housing comprising two 'spac'edside walls having opposite similar closedend grooves extendingrearward from the front of the housing and also having two transverse registering hearing notches additional to the said rearward extending grooves, arearward facing stationary contact in the housing, a contact ;e member including ajorward racing contact near one end adapted 'to engageand disengage the stationary contact, the said contact -member having between its ends; a pivot pin enteredin the reat closed ends of the atoresaid grooves, an

Operating member having apivot pin entered in the aforesaid hearing notches, the said Operating member having movement limiting stops thereon, a front cover for the housing having an opening through which a portion of the Operating member extends, the said cover engaging the pivot pin for the Operating member to holdvit in place and the said cover also engaging the stops on the Operating member to limit movement thereof in both directions, and an electro- .responsively releasable mechanical connection between the Operating member and the other end. of the contact member normally enabling the gerating member to move the contact mem- 4. The combination in an automatic circuit breaker, of an insulating housing comprising two spaced side walls having opposite similar closedend grooves extending rearward from the front of the housing and also having two transverse registering bearing notches additional to thesaid rearward extending grooves, a rearward facing stationary contact in the housing, a contact member including a forward facingcontact near one end adapted to engage and disengage the stationary contact, the said contact member having between its ends a pivot pin entered in the rear closed ends of the aforesaid grooves, a

spring applying rearward force to the contact member between the pivot pin and'the contact and thus biasing the contact member for movement in the contact disengaging direction and also tending to hold the pivot pin at the rear of the grooves, an Operating member having a pivot pin entered in the aforesaid bearing notches, and an electro-responsively releasa'ble mechanical connection between the Operating member and the other end of 'the contact member normally v enablingthe Operating member to move th contact member. i

5. The combination in an automatic circuit breaker, of an insulating housing comprising two spaced side wallshavin'g opposite similar closedend grooves extending rearward from the front of the housing and also having two transverse regiscontact disengaging direction and also tendin to hold the pivot'pin at the rear of the grooves,

an .Operating member having a pivot pin entered in the aforesaid hearing notches, an electro-responsively releasable mechanical connection between the Operating member and the other end o'f the contact member normally-enabling the operating member to move *the contact member, and a stop, engaging the contact member' near the end opposite the contact for positively pre'- venting forward movement of the contact memand diseng-age the stationary; contact which member is blased toward its open-circuit posltion, a movable actuator, an electro-responsively ,pivot portions with a connecting portion between the pivot portions, the said pivot portions of the link entering holes in the actuator and the operating member respectively and the link coop-' erating with the Operating member to form a toggle which serves when in overset relationship to normally hold the actuator and the contact member in their closed-circuit positions.

` 7. An automatic circuit breaker comprising in combination, a stationary contact, a contact member guided for movement in a fixed path and including a movable contact adapted to engage and disengage the stationary contact which member is biased toward its open-circuit position, a movable actuator, an electro-responsively controlled mechanical connection movable with the .contact member and engaging the actuator so as to enable the latter to efiect movement of the former to its closed-circuit or its open-circuit position, the said mechanical connection bein adapted to be automatically rendered inoperative upon the attainment of excess current conditions in the circuit so as to permit automatic movement of the contact member to its open-circuit'- position free from restraint by the actuator, an Operating member pivotally movable about a stationary axis, and a link consisting of a single piece of metal bent to form two parallel pivot portions with two similar transversely spaced connecting portions between the respective ends of the pivot portions, the said pivot portions of the link entering holes in the actuator and'the Operating member respectively and the link cooperating with the Operating member to form a toggle which serves when in overset relationship to normally hold the actuator and the contact member in their closed-circuit positions.

8. An automatic circuit breaker comprising in combination, a rigidly supported stationary contact, a contact member guided for movement in a fixed path and including a movable contact rigidly carried thereby and adapted to engage and disengage the stationary contact which member is biased toward its open-circuit position, a movable actuator, an electro-res'ponsively controlled mechanical connection movable with the contact member and engaging the actuator so as to enable the latter to eifect movement of the former to its closed-circuit or its open-circuit position, the said mechanical connection being adapted to bautomatically rendered inoperative upon the attainment of excess current conditions: in the circuit so as to permit automatic movement of the contact member to its open-circuit position free from restraint by the actuator, an Operating member pivotally movable about a stationary axis, and a link consisting of a single piece of metal bent to form two .parallel pivot portions ,with a resilient loop portion between the pivot portions, the said pivot portions of the link entering holes in the actuator and the Operating member respectively and the link cooperating with the operating member to form a toggle which serves when in overset relationship to normally hold the -actuator and the contact member in their closed-circuit positions and .to apply to the contact member the force necessary to provide the required pressure between the contacts.

9. An automatic circuit breaker comprising in combination,'a`rigidly supported stationary contact, a contact member guided for movement in a fixed path and including a movable contact rigidly carried thereby and adapted to engage and disengage the stationary contact which memberis I biased toward its open-.circuit position, 'a movable actuator, an electro responsively controlled mechanica-l connection movable with the contact 4 member and engaging the actuator so as to enable the latter to eflect movement of the former to its closed-circuit or its open-circuit position, the said mecha'nical connection being adapted to be automatically rendered inoperative upon the attainment of excess current conditions .in the circuit so as to permit automatic movement of the i in their closed-circuit positions and to apply to the contact member the force necessary to provide the required pressure between 'the contacts.

10. In 'an automatic 'circuit breaker, the combination of a stationary contact, a pivoted contact member including a movable contact adapt- 'ed to e a e and disengage the stationary contact, a movable actuator, an electro-responsively controlled mechanical connection mov-- able with the contact member and engaging the actuator so as to enablethe ,letter to effect movement of the former to its closedcircuit or its-open-circuit position, the said mechanica connection being adapted to be auto- `matically rendered inoperative upon the attainnent of excess current conditions in the circuit so. as'to permit' automatic movement of the contact member to its open-circuit position free from restraint by the actuator, a pivotally movable Operating member, a link pivotally connected between the actuator and the Operating member and cooperating with the Operating member 'toi'orm a toggle which serves when in overset relationship to normally hold the actuatoriand the contact member in their closed-circuit positions, and a single spring connected with the contact member and with the Operating member and serving to bias both of them for movement toward their open-circuit positions' 11. In combination in an' automatic circuit breaker, a contact biased for movement to break e the' circuit, releasable mechanism normally h'old'- ing the contactin closed-circuit position and including a. bi-metallic-element held at one end and capable of deflectiontq cause the other end to relatively move and thereby eil'ect ,the release of the 'inechanism, the said element being de-.

flectible byheat resulting from the attainment 'of excess current conditions in the circuit, a

metallic plate 'having' a longitudinal slot near aaoaaio one edge which provides a readily distortable edge portion to whichthe first said end of the bi-metallic element is rigidiy Secured, and means associatedwith the metallic plate for distorting the said distortable edge portion thereof in a direction peralle] with the faces of the plate so as to change the relationship of the said bimetallic element with respect to the main body of the plate and thereby change the eifectiveness of the deflection `for causing the release of the mechanism.

12. In combination in an automatic circuit breaker, a contact biased for movement to break the circuit, releasable mechanism normally holding the contact in closed-circuit position and including a bi-metalli'c element held at one end v and capable of deflection to cause the other end to relatively move and thereby eiiect the release of the mechanism, the said element being defiectible by heat resulting from the attainment of excess current conditions in the circuit, a metallic plate, having a longitudinal slot near one edge which is closed at its ends and which' provides a readily distortable edge portion to which the first said end of' the bi-metallic element metallic plate for distorting the said distortable edge portion thereof so as to change the relation- 'shipni the said bi-metallic element with respect to the main body of the plate and thereby change the efiectiveness of the deflection for causing the release of the mechanism. i

13. In combination in an automatic circuit 'is rigidly Secured, and means associated with the breaker, a contact biased for movement to break the circuit, releasable mechanism normally ho1ding the contact in closed-circuit position and ,including a bi-metallic element held at one end and ca'pable ot deflection to cause the'other end to relatively move and thereby efiect the release of the mechanism, the said element beingdeflectible by h'eat resulting from the attainment of excess current' conditions in the circuit, a metallic plate having 'a threaded hole therein near one edge and also having therein a longitudinal slot which intersects the hole and which provides a readily distortable edge portion to which the 'first said end of the bi-metallic element is rigidly Secured, 'and a tapered screw extending into the threaded hole for distorting thesaid distortable edge portion of the metallic plate so as to change the relationship of the said bi-metallic element thereby change the cflectiveness oi the deflection for causing the release of the mechanism.

14. In an automatic circuit breaker, the com- .with respect to the main body 'of the plate and bination of a stationary contact, a movable contact member having a, contact adapted to. engage and disengage the stationary contact, the said contact member comprising ametallic plate having a longitudinal slot near one edge which provides a readily distortable edge portion, a bimeta'llic element adapted to be heated and de flected upon the attainment of excess current conditions in the circuit, the said element having one end tree and having the other end rigidly Secured to the. said-distortable edge portion of ,the contactmember, an actuator movable with the contact member and 'normally engaged by the tree' end of the bi-metallic element but disi ensaged thereby upon deflection means for moving the actuator to thereby normally eii'ect movement ot the bi-metalic element and' the contact member, and means associated with the metallic plate oi' the contact member for disto'rting' the said distortable edge portion flereot seas to thereby change the relationship of the bi-metallic element with respect to the main body of the contact member and with respect to the actuator.

15. In an automatic circuit breaker, the combination of a stationary contact, a movable contact member having a contact adapted to engage and disengage the stationary contact, the said contact member comprising a metallic plate having a longitudinal slot near one edge which is closed at its ends and which provides a readily distortable edge portion, a bi-metallic element adapted to be heated and defle'cted upon the attainment of excess current conditions in the circuit, the said element having oneend free and having the other end rigidly secured to the said distortable edge portion of the contact member, an actuator movable with the contact member and normally engaged by the free end of` the bi-metallic element but disengaged ,thereby upon deflection, means for moving the actuator to thereby normally effect movement of the bimetallic element and the contact member, and means associated with the metallic plate of the contact member for distorting the said distortable edge portion thereof so as to thereby change the relationship of the bi-metallic element with respect to the main body of the contact member and with respect to the actuator.

16. In an automatic circuit breaker, the combinationof a stationary contact, a movable contact member having a contact adapted to engage and disengage the stationary contact, the said contact member comprising a metallic plate having a threaded hole therein near one edge and also having thei-ein a longitudnal slot which intersects the hole and which provides a readily distortable edge portion, a bi-metallic element adapted to be heated and defiected upon the attainment of excess current conditions in the circuit, the said element having one end free and having the other end rigidly Secured to the said distortable edge portion of the contact member, an aotuator movable with the contact member and normally engaged by the free end of the bi-metallic strip but disengaged therefrom upon defiection, means for moving the actuator to thereby normally efiect movement of the bimetallic element and the contact member, and a tapered screw extendng into the threaded hole -in the metallic plate of the contact member for distortng the said distortable edge portion thereof so as to thereby change the relationship of the bi-metallic element with respect to the main body of the contact member and with respect to the actuator.

PAUL M. CI-IRISTENSEN. 

